This study is designed to test the effectiveness of a combination of the investigational drug, "Nal-Glu" GnRH antagonist, plus testosterone enanthate (TE), as a potential male contraceptive regimen in healthy young men. Specifically, we would like to determine whether this combinatino of drugs suppresses sperm counts to azoospermia (zero sperm) or to severe oligospermia (3 million/mL) more quickoy and in a greater percentage of men than does TE given by itself.